Preheat oven to 375° F. Paper line 18 muffin cups.
Combine flour, granulated sugar, brown sugar, baking powder and salt in large bowl.
2 cups all-purpose flour, 1/2 cup granulated sugar, 1/4 cup brown sugar, 2 1/2 tsp baking powder, 1/2 tsp Salt
Stir in milk, egg, butter and lemon peel. Stir in 1 1/2 cups morsels and blueberries. Spoon into prepared muffin cups, filling almost full. Sprinkle with Streusel Topping if using.
3/4 cup milk, 1 large eggs, 1/2 tsp lemon peel, 12 oz white chocolate chips, 1 1/2 cups blueberries, Streusel Topping, 1/4 cup butter
Bake for 22 to 25 minutes or until wooden pick inserted in center comes out clean. Cool in pans for 5 minutes; remove to wire racks to cool slightly.
Place remaining morsels in small, heavy-duty plastic bag. Microwave on MEDIUM-HIGH (70%) power for 30 seconds; knead. Microwave at additional 10- to 20-second intervals, kneading until smooth. Cut tiny corner from bag; squeeze to drizzle over muffins. Serve warm.